PROJECT SUMMARY The Biostatistics Core is a shared resource for biostatistics, study design, and data management for the constituent projects of the Alcohol Research Center for HIV (ARCH). Led by Dr Joseph Hogan, a senior statistician with expertise in statistical methods for HIV and behavioral sciences, the Biostatistics Core is designed to provide faculty-level research collaboration for Center investigators, computing support for implementing data analyses, training modules for trainees and early career researchers, and outreach to investigators with interest in expanding the scope of research on HIV and alcohol at Brown, affiliated hospitals, and institutions within the ARCH collaboration. In the initial funding period, core faculty established strong and highly productive working relationships with the leaders of ARCH research projects. The Core will continue to ensure that the best practices in the areas of data analysis and study design are used and maintained, and that a uniformly high standard is applied to all projects supported by the ARCH. In turn, collaborations between projects leaders and Core faculty will continue to lead to improvements and refinements in statistical methodology, opening up new areas of quantitative research. Having the Core will create an economy of scale, whereby statistical methods used in one study can be more easily applied to another one, obviating the need for each study to 'reinvent the wheel' where analytic methods are concerned. Finally we expect the Core to make new projects highly competitive for external funding, by providing ready access to faculty statisticians who will provide input on aspects of study design, analysis, and the use of modern and up-to-date methods for statistical inference; and by providing training and mentorship to junior faculty in the area of design and analysis. Core faculty have made substantial contributions to the research and training agenda of ARCH, leading or collaborating on publications related to neuroimaging analysis, gene expression data, and causal mediation analysis. The core delivered a popular one-day course on causal inference in behavioral sciences. Data management personnel began implementation of data harmonization across the constituent projects, and oversaw the configuration of a secure FTP for data exchange and project archives.